1. Technical Field
The present invention relates to a method for producing an oscillator.
2. Related Art
There has been an increase in the development of technologies related to MEMS (Micro-Electro-Mechanical System) in the field of acceleration sensors and video devices. MEMS refers to a very small functional device produced using a semiconductor production technique, and is produced on the basis of a microprocessing technique in the semiconductor production of the related art. Examples of the functional device to be produced include microoscillators, microsensors, and microactuators, and the functional device exhibits a variety of functions by oscillation, deformation, or other action of a microstructure (see, for example, JP-A-2007-160495).
In the case of a functional device which detects a variety of physical amounts by oscillating or deforming a microstructure, the structure may be essentially damaged due to the oscillation or deformation. In particular, to a bend region or a flexure region of an oscillator or the like, stress is repeatedly applied, and therefore, it is desirable to design the structure so that such stress does not concentrate on a specific region as much as possible. Further, for example, in the case where a groove, a hole, a defect, or the like is formed in the structure, stress concentration due to bend or flexure is liable to occur particularly prominently in the region where a groove, a hole, a defect, or the like is formed.
In the case where such an oscillator or the like is formed by a microprocessing technique of the related art in the semiconductor production, the shape after processing may be sometimes problematic, although it is not problematic in the semiconductor production. For example, in the case where an electrode is formed on a substrate, when it is formed by a microprocessing technique of the related art, a small angular portion is sometimes formed in the vicinity of an edge of the electrode. Such an angular portion is not a big problem in a semiconductor device having no bend region or flexure region. However, in the case where an oscillator or the like having a fixed electrode and a movable electrode disposed to face the fixed electrode is produced, for example, if a small angular portion is formed on the fixed electrode, an inappropriate groove derived from the angular portion of the fixed electrode is sometimes formed on the movable electrode to be formed after forming the fixed electrode. In this case, stress concentration is liable to occur in the groove of the movable electrode corresponding to the bend region or the flexure region of the oscillator, and the reliability of the oscillator may be deteriorated. Further, a short circuit may occur due to the contact between the angular portion of the fixed electrode and the movable electrode.